Facies and geochemistry of non-marine gypsum, EMISAL, Egypt
Diverse gypsum facies in terms of crystal size and morphology are deposited in a shallow, non-marine, sulfate-enriched, semi-closed, perennial evaporite basin. These gypsum facies were deposited in intimate association with cyanobacterial mats. Facies analyses and geochemistry revealed two distinct...
| Autores: | , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2013 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:115538 |
| Acceso en línea: | https://ddd.uab.cat/record/115538 https://dx.doi.org/urn:doi:10.1344/105.000002051 |
| Access Level: | acceso abierto |
| Palabra clave: | Gypsum Lithofacies Non-marine Geochemistry |
| Sumario: | Diverse gypsum facies in terms of crystal size and morphology are deposited in a shallow, non-marine, sulfate-enriched, semi-closed, perennial evaporite basin. These gypsum facies were deposited in intimate association with cyanobacterial mats. Facies analyses and geochemistry revealed two distinct primary facies, based on gypsum fabric; massive selenite, and laminated gypsum varieties. The massive selenite facies is composed of clusters of single and twinned crystals along (100), with upward pointing re-entrant angle. The laminated gypsum varies from rhythmically laminated grass-like selenite to gypsum microbialite (stromatolite). The change from massive selenite to laminated gypsum facies implies fluctuation in lateral and vertical salinity profiles, seasonal brine concentrations and wind action. Post-depositional changes in the form of dissolution, slight to moderate crystal deformation and recrystallization to anhydrite are evaluated. We develop a qualitative model for the depositional basin and facies distribution in order to simulate ancient analogues. |
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